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The crew was provided with the latest available weather sequence reports for their route before departure from Washington.
The ground witnesses reported that the weather in the incident area, and along the last segment of flight from Holston Mountain, was clear and calm, with a few high scattered clouds. The accident occurred in day VFR conditions about 1:40 before sunset.
1.8 Aids to Navigation
There were no reported discrepancies of ground or airborn navigation equipment during the flight. The aircraft came under radar observation and control the Atlanta Air Route Traffic Control Center at 1735. Both primary and secondary radar targets[1] were observed until they disappeared at 1813:30, some 15 minutes after passing Holston Mountain VOR. The center's radar had been flight checked as usable down to 6,000 feet m.s.l. along Victor 16 from Holston Mountain VOR to the Ottway Intersection 39 miles southwest of the VOR. Radar beacon targets had been observed along this portion of Victor 16 down to an altitude of 4,000 feet m.s.l. The last altimeter setting given the crew of Flight 823 was 29.87 inches for Knoxville by Atlanta Center.
The Knoxville VORTAC was operational during the period Flight 823 was flying between Holston Mountain and Knoxville.
1.9 Communications
There were no reported discrepancies in air to ground communications during the flight from Washington to Holston Mountain.
The flight was observed on radar to pass Holston Mountain VOR at 1757. The crew called at 1758:35 and reported passing Holston Mountain 1758. At 1759:45 the flight requested the "lowest altitude available" and was cleared to descend to and maintain 8,000 feet. At 1802:45 the flight cancelled their IFR clearance. At that time the Atlanta controller offered to hand the flight off to Knoxville Approach Control when it got a little closer in, if they would stand by on the Center frequency. At 1802:55 the flight acknowledged this transmission with "OK." This was the last known transmission from the flight.
At 1814:10 the Atlanta controller called the flight to report his loss of radar contact but received no reply. All other attempts by him to contact Flight 823 were fruitless.
There was no evidence of an emergency or any unusual situation in any transmission by the crew.
1.10 Aerodrome and Ground Facilities
Not involved in this accident.
- ↑ Primary radar targets are reflections from the aircraft surfaces. Secondary radar targets are electronic returns from a radar transponder aboard the aircraft.
